Curcumin, a polyphenol isolated from the plant turmeric, is recognized for its anti-inflammatory and anti- tumorigenic bioactivities. It is currenly being evaluated in multiple clinical trials for the prevention or treatment of cancers of the colon rectum, pancreas, multiple myeloma, and also for neurodegenerative diseases. Although a plethora of in vitro targets of curcumin have been identified, the precise molecular mechanism(s) of its biological activities have not been uncovered. Low oral bioavailability and rapid reductive metabolism and conjugation limit the clinical use of curcumin. We have recently discovered a novel, previously unrecognized oxidative transformation of curcumin. In preliminary experiments we have detected the major oxidative metabolite of curcumin in plasma and intestinal mucosa after oral administration of curcumin to mice. The reaction of curcumin with molecular oxygen is rapid, prominent, and gives rise to novel and reactive metabolites that could potentially explain some of the pharmacological effects of curcumin. In preliminary studies we have shown that these metabolites contribute to the regulation of cellular antioxidant response and form covalent DNA adducts. The goal of this grant application is to characterize pharmacokinetics, tissue distribution, and metabolism of the oxidative metabolites of curcumin in the mouse and in human liver microsomes. The following specific aims will be performed: (1) To develop a specific and accurate isotope- dilution based LC-MS quantification method for curcumin and its oxididative and reductive metabolites; (2) To identify and quantify oxidative metabolites of curcumin in cultured cells and in human liver microsomes; (3) To perform a pharmacokinetic and tissue distribution analysis of curcumin and its oxidative and reductive metabolites in the mouse. Our research plan is designed to define the in vivo formation, abundance, and distribution of oxidative metabolites of curcumin. The transformation of curcumin into reactive and oxygenated metabolites could be mediating some of the biological effects of curcumin, and could ultimately lead to a novel understanding of the biochemistry and pharmacology of curcumin. PUBLIC HEALTH RELEVANCE: Increasing biochemical and clinical evidence supports the use of the dietary supplement curcumin for the prevention of cancer. The goal of this application is to characterize the in vivo formation and abundance of novel metabolites of curcumin that could be involved in its biological activity.